Question

Zener breakdown occurs in a p-n junction having p and n both

• A. lightly doped and have a wide depletion layer
• B. heavily doped and have a narrow depletion layer
• C. heavily doped and have a wide depletion layer
• D. lightly doped and have a narrow depletion layer

Answer 1

The correct option is B

heavily doped and have a narrow depletion layer

Explanations for correct option b:
ZENER DIODE BREAKDOWN

1. A Zener diode is a semiconductor with P-N junctions. The current can flow in forward or backward direction in it.
2. When the reverse-biased voltage applied to the P-N junction is increased, the current increases rapidly. Even a small change in voltage increases the current amount. This rapid fluctuation in current causes the junction to break down and this breakdown is called Zener diode breakdown.

DOPING OF DIODE

1. A diode is doped which means the number of electrons and holes are varied in it.
2. When the Zener diode breaks down,it has both the P and N junctions heavily doped which means there is a higher concentration of electrons as compared to holes.
3. It is a region where no mobile-charged carriers are present. It also acts as a barrier for the transfer of electrons from the N side to the holes of the P side.
4. Depletion layer width is inversely proportional to the amount of doping of the diode.

DEPLETION LAYER

Therefore, in a P-N junction, while the Zener diode breaks down, p and n are highly doped with a narrow depletion layer.

Hence, the correct option is (C).